fix: repair invite links, social features, messaging + Discord UI overhaul

Phase 1 - Feature Repair:
- Fix member kick/leave: add missing db.delete() call in servers.ts
- Stabilize invite codes: return existing code instead of regenerating
- Fix user search: use LIKE instead of exact match in social.ts
- Wire DM button on FriendsPage to create/navigate to DM channels
- Add cancel outgoing friend request (DELETE endpoint + frontend)
- Add accept/decline friend request actions with WS real-time events
- Fix replyToId persistence in message creation
- Hydrate reactions and replyTo in message queries
- Add joinByCode to API client and serverStore
- Add friend_request_received/accepted WebSocket events

Phase 2 - Discord UI Overhaul:
- Remove stray borders between layout columns
- Replace shadow-sm with shadow-header on content headers
- Replace all bg-gray-*/text-gray-* with Discord color tokens
- Ensure flat color contrast (#1E1F22, #2B2D31, #313338)

Testing:
- Set up vitest + @testing-library/react + jsdom
- Add 17 tests across InviteModal, JoinServer, FriendsPage (all passing)
- Fix vite resolve.extensions to prefer .tsx over stale .js files

packages/web/src/stores/uiStore.ts

@@ -1,4 +1,5 @@
 import { create } from 'zustand';
+import type { User } from '@opencord/shared';
 
 type ModalType =
   | 'createServer'
@@ -18,6 +19,10 @@ interface UIState {
   isMobile: boolean;
   showDms: boolean;
   imagePreviewUrl: string | null;
+  userProfilePopout: {
+    user: User | null;
+    position: { top: number; left: number } | null;
+  };
   toggleSidebar: () => void;
   toggleMemberList: () => void;
   openModal: (modal: ModalType, data?: Record<string, unknown>) => void;
@@ -26,6 +31,8 @@ interface UIState {
   setShowDms: (show: boolean) => void;
   openImagePreview: (url: string) => void;
   closeImagePreview: () => void;
+  openUserProfile: (user: User, position: { top: number; left: number }) => void;
+  closeUserProfile: () => void;
 }
 
 export const useUIStore = create<UIState>((set) => ({
@@ -36,6 +43,10 @@ export const useUIStore = create<UIState>((set) => ({
   isMobile: false,
   showDms: false,
   imagePreviewUrl: null,
+  userProfilePopout: {
+    user: null,
+    position: null,
+  },
 
   toggleSidebar: () => set((state) => ({ sidebarOpen: !state.sidebarOpen })),
   toggleMemberList: () => set((state) => ({ memberListOpen: !state.memberListOpen })),
@@ -53,4 +64,11 @@ export const useUIStore = create<UIState>((set) => ({
 
   openImagePreview: (url) => set({ activeModal: 'imagePreview', imagePreviewUrl: url }),
   closeImagePreview: () => set({ activeModal: null, imagePreviewUrl: null }),
+
+  openUserProfile: (user, position) => set({
+    userProfilePopout: { user, position }
+  }),
+  closeUserProfile: () => set({
+    userProfilePopout: { user: null, position: null }
+  }),
 }));